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Quasiparticle heterodyne mixing in SIS tunnel junctions

Journal Article · · Appl. Phys. Lett.; (United States)
DOI:https://doi.org/10.1063/1.90782· OSTI ID:6458319

The rapid onset of quasiparitcle tunneling current in superconductor-insulator-superconductor (Josephson) junctions at voltages above 2..delta../e is being used for millimeter-wave heterodyne mixing. Junctions with a 2-..mu..m diameter and R/sub N/=50 ..cap omega.. have little capacitive shunting at the signal frequency of 36 GHz. Because there is no series resistance, residual capacitance can be tuned out. Double sideband conversion efficiencies of 0.32 and mixer noise temperatures as low as T/sub M/< or =7 K=4h..nu../k have been observed. The results are compared with shot-noise-limited mixer theory. Photon-assisted tunneling effects are seen which indicate the approach to photon-noise-limited operation.

Research Organization:
Department of Physics, University of California, Berkeley, California 94720
OSTI ID:
6458319
Journal Information:
Appl. Phys. Lett.; (United States), Journal Name: Appl. Phys. Lett.; (United States) Vol. 34:5; ISSN APPLA
Country of Publication:
United States
Language:
English